How to Use Hydroponic Growing Systems for Marijuana

The quick and simple guide...
Nicole Richter / Updated on August 15, 2018

Hydroponic Growing

If you’re a newcomer to the world of marijuana growing, you’re probably still 100% sure that you need soil to grow your plants, right? If so, you are incorrect, because there are also hydroponic gardening systems specifically designed to grow weed without the need for soil.

Although a hydroponics growing system probably seems like something from the future, its roots lie firmly in the past. Ancient civilizations knew how to plant weed and were experimenting with hydroponics thousands of years ago. It has been suggested that the famed Hanging Gardens of Babylon were created using such systems.

Whether or not you believe that King Nebuchadnezzar II helped build the gardens in the 6th century BC or not, it does seem likely that the Aztecs used hydroponics for farming in 10th century Mexico.

In the modern era, hydroponic systems create some of the world’s most fragrant and potent cannabis. Keep reading to discover how to grow marijuana indoors using the best hydroponic system for your needs.

What is Hydroponic Cannabis?

Hydroponic marijuana simply refers to a means of growing using a soilless hydroponic system; in other words, you grow plants using an inert growing medium and nutrient-rich solutions. In the past, it was assumed that hydroponic setups were complicated and expensive affairs designed solely for commercial growth. In reality, however, you can engage in weed growing with hydroponics using something as simple as a few pots that contain the inert medium. By all means, you can opt for a more complicated option but it requires significant setup time and a ton of maintenance.

Growing cannabis hydroponically has become an increasingly popular method because of the issues associated with using soil. It is a much better option for indoor growers who face the following problems when growing weed ‘traditionally’ using soil:

  • A constant need to monitor the pH of the soil.
  • Ascertaining the correct level of nutrients is hard.
  • There is always a potential problem with pests.
  • You might not be able to recycle the soil you use.
  • You have to choose the best soil because its quality dictates the size and potency of your final product.

The biggest hurdle to overcome by using soil is nutrient intake. Organic matter decomposes in soil and then breaks down into nutrients such as Nitrogen (N), Phosphorus (P), and Potassium (K). The nutrients are dissolved in water and absorbed by the plant’s roots.

Everything needs to be balanced perfectly in the soil if you want your marijuana plant to get the ideal nutrient intake. When using soil, you have to contend with biological imbalances, insufficient organic matter, and contamination, which makes perfect balance an impossibility. With a hydroponic system, you can provide cannabis with the right nutrient balance and ensure that it goes straight to the plant’s roots.

Overall, soil loses a lot of nutrients, and it is difficult to measure its pH. When you use a hydroponic setup, it is much easier to determine pH and adjust as necessary. In soil, you can only dissolve the nutrients when you water your plants. When you grow weed hydroponically, everything is dissolved in water automatically, ensuring there is always plenty of moisture. Also, as these systems are sterile, the threat of pests is significantly reduced.

Pros & Cons of Hydroponic Cannabis Growth

Although it is not the perfect weed growing technique, there are a lot of advantages to hydroponic systems, and they significantly outweigh the disadvantages, as you will see.

Pros for growing hydroponic weed:

  • As you don’t need soil, you have a system that is cleaner and easier to use.
  • Hydroponics involves using a controlled system which means less nutrient pollution gets released into the environment.
  • The water remains in the system, allowing you to reuse it.
  • If you elect to use Rockwool as your inert growing medium, there is no additional repotting labor.
  • Overall, hydroponic marijuana yields are larger than their soil counterparts and produce potent weed with bigger buds and better aromatics.
  • You don’t have to worry about root drowning and dry spots.
  • There is less risk of damage caused by pests and diseases; it is also far easier to tackle such threats.
  • Hydroponics enables the weed to grow faster.
  • You can use this setup in places such as your bedroom.

Cons for growing hydroponic weed:

  • Hydroponics systems are expensive to set up.
  • It requires a lot of maintenance. For example, you have to keep a close eye on pH levels.
  • It requires a lot of electricity.
  • Although it is easier to ensure your plants get enough nutrients, mistakes can be very costly.
  • Hydroponics requires a LOT of water. For example, a large plant could need up to a gallon of water a day, so there is always a danger of the system running out of water.
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Setting Up Your Hydroponic Cannabis Growing System

There are several hydroponic gardening systems to choose from, and all of them are suitable for growing cannabis indoors. Regardless of the method you use, the overall tactic involves the use of a reservoir containing the nutrient solution which is placed beneath a growing tray. This tray contains the inert growth medium of your choice, such as sand, gravel, or Rockwool.

Hydroponic weed involves growing the plant in the medium, where it develops a set of roots and a stem. The roots grow through the medium and into the nutrients, and you use a small pump with a timer to fill the bottom layer with the nutrient solution. After an allotted period where the plants are fed and watered, the timer shuts off the pump, and the solution drains back into the reservoir.

The hanging root structure of the plants means they are constantly exposed to air, and the result is a crop of flourishing plants. Your cannabis plants can use their energy for the sole purpose of maximizing growth. With soil, they waste energy trying to find air, food, and water. This is why weed grows so spectacularly in a well-designed hydroponics garden.

There is a multitude of indoor hydroponic systems to choose from, but we will only focus on the best known.

Ebb & Flow Hydroponics

This all-in-one system is arguably the most popular method of growing weed hydroponically. You grow the plant in the inert medium and wait for it to develop its roots and stem; the roots grow through the medium and into the solution. A basic system involves growing individual plants in pots containing a medium such as Rockwool cubes. These pots are placed on a table known as a ‘growing bed.’

The bed holds around two inches of solution which is pumped onto the bed where it floods the growth medium from the bottom up. It pushes out oxygen, and when the liquid reaches its highest level, a drain pipe is filled. This system also involves the use of a timer, which activates the pump. It floods the medium at set intervals with the nutrients before draining the solution out.

Typically, an ebb and flow system involves the use of two plastic tubs with one sitting inside another. The top tub contains the plants, while the bottom tub includes the nutrient reservoir, an air stone, and a water pump. There is a small hole in the top tub so that the pump’s tubing can fit inside. Therefore, when the pump shuts off, or if there is a problem with the pump, the water will drain into the hole from where it came from.

Experienced growers know that it is wise to place an extra hole in the system so that it drains down to the bottom tub at the maximum level you want the water to reach, as this prevents flooding. Most people opt for 15 or 30-minute on and off cycles. The main issue with the Ebb and Flow system is that you have to monitor it constantly. If you don’t spot a pump failure immediately, your plants can die very quickly.

Nutrient Film Technique (NFT)

This is another all-in-one system and involves pumping the nutrient solution from the reservoir to the planting tube using large PVC tubing angled at a small decline. By doing this, you ensure the solution drains down the tube and passes all of the plant’s roots before being recycled in the holding tank.

One of the biggest problems with the NFT system is that the solution doesn’t always exit the tube. The resulting stagnant water left in the channel can lead to the growth of bacteria which kills your plants. This is why you have to angle the tube. On the plus side, an NFT system is easy to expand. Simply add more holes to the planting tube or add more tubes to expand your grow.

Drip Irrigation System

This option is mainly used in commercial hydroponics gardens, and it enables you to use one of several growth mediums. It involves the use of individual drippers that are placed in the growth medium of each plant. These drippers add equal amounts of the nutrient solution to the plants and excess that doesn’t get absorbed is drained into the reservoir and pumped back via the dripper system.

The Drip Irrigation System enables fast harvesting, and you can remove the dripper from the medium if you want to swap out plants quickly and easily. When you choose customizable flows, you can even control the precise amount of nutrient solution that each plant receives. It also allows you more control over your garden’s watering schedule so you can change watering frequency as per each plant’s requirements.

Deep Water Culture (DWC)

DWC is the most basic indoor hydroponics system, making it the best method of growing pot for beginners. Place your plants in individual containers and add them to a grow tray suspended in water. Your water tank has an air pump that ensures the water remains oxygenated, and a nutrient solution is added to feed the plant’s roots. The air pumps allow you to keep the roots submerged in water because they continually receive oxygen.

Aeroponics

This is possibly the most unique method of growing pot on the list. With this system, you take an oxygenated nutrient solution from the reservoir and pump it into misting valves. They spray the mist into a group of chambers where the roots are exposed. In the great aeroponics vs. hydroponics debate, the former method ensures that your plant’s roots receive the highest level of oxygen.

On the downside, an aeroponics system is extremely expensive and is typically only used by commercial growers. If the misting valves become clogged, your plants will die as their roots are unable to receive moisture. One bonus of using aeroponics is that you are growing your marijuana vertically, which means getting the maximum out of your available space.

The Wick System

This is another basic hydroponics system. It involves using a material such as rope slotted through a PVC tube. The nutrients solution is pulled up the rope and added to the growing tray. One advantage of the Wick System is that you don’t need a water pump. It is probably the best way to grow marijuana hydroponically until you determine whether it is the right method for you.

Choosing the Right Hydroponic Growing Supplies

There is a lot of work involved in growing your own weed via a hydroponics gardening system. Ideally, you will invest in a variety of measuring instruments, nutrients, and growth mediums. Let’s take a look at your potential options.

Growth Mediums

Although you are not using soil when growing hydroponically, you do need a stable base for the plants to grow their roots through and also to hold up the plant’s weight. Please bear in mind that none of these options provide any nutrients. Their main role is to provide support for the roots because the hydroponic solution you choose contains all of the nutrients. Here is a list of growing medium options:

Rockwool

Rockwool is rock spun into a material akin to the spun glass used as insulation. Its ability to breathe and retain moisture ensures that it remains a firm favorite in hydroponics systems. Rockwool is available in multiple cube-shaped sizes. You can use small cubes for seedlings and larger ones for systems such as Ebb and Flow.

When you purchase Rockwool, submerge it in water for at least eight hours to remove any air bubbles. Rockwool cubes are specially created for hydroponics systems and contain pre-set holes that you place your plants into. It is inexpensive, reusable and impossible to overwater.

The main disadvantage when using Rockwool cubes is the environmental cost. Otherwise, it is an excellent option for hydroponics cannabis. If you opt for Rockwool, bear in mind that its pH is 7.7, so you have to lower it to between 5.8 and 6.3. You can do this by soaking it in pH adjusted water. A lot of growers add vinegar to the nutrient solution. Once you have treated the cubes, check their pH one last time before adding plants.

Perlite

This porous white substance retains and wicks moisture extremely well. Generally speaking, you should purchase large chunks rather than the small granules it is normally sold in. The surface of each perlite particle is covered with miniature cavities – the result is a very large surface area which holds nutrients and moisture. It is a sterile substance, so there is no danger of pests, insects, or disease.

Vermiculite

This is another crushed volcanic rock medium like perlite, and is also known for its terrific drainage. Although it is sterile, vermiculite is not normally used as a growing medium by itself, with growers electing to mix it with perlite. If you decide to use it, ask the seller where it was sourced, as vermiculite that comes from Africa is very alkaline, with a pH of up to 9.0.

Coconut Fiber

This is a relatively new hydroponic cannabis growing medium and is similar to Rockwool, the difference being that it is more sustainable. It has a certain level of buffering ability akin to soil, retains moisture reasonably well, but contains hardly any nutrients. One major bonus when using coconut fiber is that it contains plant-stimulating hormones that increase the roots’ protection from disease and infection.

Clay Pellets

This is another reusable medium that is heavy enough to support plants but is still easy to work with. These pellets wick moisture toward a marijuana plant’s roots and enable oxygen to flow through.

What About Additional Equipment?

Before we go into nutrients in greater detail, be aware that proper hydroponics gardens require a significant amount of equipment. You can, of course, choose a simple system to minimize what you need, but for the best results it is worth investing in measuring instruments. Remember, good hydroponics growing involves constant monitoring of nutrients so you can quickly correct imbalances. As a result, you should strongly consider investing in a pH and PPM meter.

  • pH Meter: In general, most marijuana strains grow best hydroponically with a pH level of 6.0. With a pH meter, you can measure your nutrient solution’s pH daily to keep it at an optimal level.
  • PPM-EC Meter: This measures the water’s electrical conductivity which is higher when more minerals are dissolved in the water. With this meter, you can prevent under- or overfeeding.
  • PPM-TDS: This is a more sophisticated meter which measures the amount of plant food in water. If you want an accurate PPM measurement, measure your water’s PPM level, add nutrients, and measure again.

Overall, you should keep the pH level between 5.8 and 6.3, although you will get away with a range of 5.5 – 6.5. As for PPM, make sure the range is between 900 and 2800 depending on your marijuana’s growth phase.

You should be able to find so-called ‘plug and play’ hydroponic systems that provide everything you need to get started. Even so, here is a basic list of things you’ll need for a starter system:

  • One large (3 – 5 gallon) bucket per plant.
  • A water pump.
  • An air pump.
  • A reservoir tank.
  • An air stone.
  • A grow table.
  • A growing medium such as Rockwool or clay pellets.
  • Plastic tubing.
  • A drip line and up to two drip line emitters for each plant.

Nutrients for Hydroponic Cannabis

With a hydroponics setup, you are responsible for providing the plant with all of its nutrients. If you get it wrong, your plants will die or produce a small and unsatisfying yield. On the plus side, a hydroponic garden ensures that your marijuana plants’ roots easily find nutrients and don’t waste energy looking for them.

The most basic tenet of growing marijuana hydroponically is to ensure that your plants get the right ratio of Nitrogen (N), Phosphorus (P), and Potassium (K). When purchasing nutrient solution, you’ll notice that it will show its N-P-K ratio. For example, a 20-10-10 solution contains 20% nitrogen, 10% phosphorus, and 10% potassium.

In your plants’ vegetative stage, look for a solution with a high level of nitrogen in particular. This is especially the case when the temperature in the growing room is 79 degrees Fahrenheit or less. A good ratio to aim for is 23-19-17 which means you have a solution packed with nitrogen. Once your plants reach the flowering stage, the emphasis switches to phosphorus, with a significant reduction in nitrogen. Shoot for a ratio of 15-30-15 regardless of the growing room’s temperature.

It is common for nutrient solutions to be deficient in magnesium. If this is the case, use Epsom salts. Other important nutrients include iron, zinc, manganese, boron, calcium, copper, and sulfur. Depending on your crop’s growth stage, it is necessary to adjust nutrient levels to optimize growth. It is also important to change your solution regularly to avoid nutrient deficiencies. When checking the pH, be especially wary of it becoming more acidic because of cationic exchange.

You should be easily able to find nutrients for your hydro growing system online or in a gardening store. They tend to come in a pre-mixed liquid or powder form. The powder is less expensive, but liquids mix with water more easily and are ideal when growing smaller crops.

When adding nutrients to your marijuana plants, take pH and EC (electrical conductivity) readings. The EC rating measures mineral content, the more minerals there are, the higher the EC reading. Typically, an EC rating of 0.8 – 2.0 is apt for growing weed. As you’re probably aware, younger plants require more nutrients than a flowering plant.

We mentioned PPM measurements above, but let’s go into greater detail. In the industry, there are ‘500’ and ‘700’ scales. Basically, you multiply the EC rating by either 500 or 700 depending on the measurement you’re using. For instance, with the 700 scale, an EC reading of 1.5 converts to 1050 PPM (700 x 1.5) but it would be 750 PPM with the 500 scale (500 x 1.5).

As we mentioned earlier, the ideal PPM depends on the growth stage. Here is a quick guide:

  • Seedlings: 100 – 250
  • Early Vegetative Stage:300 – 400
  • Late Vegetative State:450 – 700
  • Early Blooming Stage:750 – 950
  • Full Bloom:1,000 – 1,600

Tips for Growing Your Hydroponic Cannabis

It should go without saying that using a hydroponic growth system is very different from traditional methods of growing weed indoors. As a result, there are a few things to consider when trying to grow marijuana plants in a hydroponic garden system.

Sterile Equipment

It is impossible to overstate the importance of using clean equipment at the very beginning. All tanks, reservoirs, filters, pipes and other equipment must be sterile to prevent the development and spread of bacteria. Although hydroponic systems are less susceptible to diseases, they will run rampant if left unattended. It is a good idea to have multiple bottles of hydrogen peroxide and isopropyl alcohol on hand to disinfect your equipment.

Water pH

Make sure that pH neutral water at 7.0 is circulating through your hydroponics system. You can create a reverse osmosis (RO) system to create and provide pH neutral water. Alternatively, purchase distilled water until you’re able to develop the RO system.

Temperature Considerations

It is best if the water flowing through your system is at a temperature of 65 degrees Fahrenheit. This is the ideal temperature for nutrient absorption, and it also prevents algae buildup. As for your growing room’s temperature, keep it at 75 degrees Fahrenheit to begin with.

Humidity

When growing pot indoors, maintaining the right humidity levels is a constant challenge. You have to begin with relatively high humidity and dial it down as your plants grow. As seedlings and in the vegetative state, keep the humidity in the 60-70% range. Reduce by up to 5% weekly until it is at around 40% during the blooming stage. You may need to purchase a humidifier and a dehumidifier to achieve these targets.

Lighting

There is no ‘right’ lighting setup, only the best one for your grow space and budget. For example, if you have a large room with excellent ventilation and airflow, you can purchase High-Intensity Discharge (HID) lights. If you have a smaller growing room, try Light Emitting Diode (LED) fixtures or Compact Fluorescent Lights (CFLs) if you have a smaller budget. Overall, choose lighting that produces a sufficient amount of light between 400 and 700 nanometers.

Airflow

Good airflow helps keep temperatures at the right level. Invest in a few fans and place them strategically in your growing room.

Keep Records

Regardless of whether this is your first grow or you’re a veteran, it is essential to keep detailed records of your crop’s growth. It is not unusual for novices to enjoy spectacular success, only to realize that they failed to record any data. Important notes include pH levels, planting dates, EC measurements, temperature, and humidity.

Cannabis Grown with Soil vs. Hydroponics

There are those who believe that a hydroponic grow system is the only way we should be growing cannabis. Although there are many benefits of hydroponics, should we be so keen to dismiss the age-old practice of growing in soil? After all, there are a few downsides associated with using a hydro system.

First and foremost, marijuana plants grown via indoor hydroponic systems are more likely to tip or break. One way to avoid this problem is by trellising your garden (adding support fences for the plants to grow on)  as it helps your plants to grow in a specific direction.

One of the big benefits of hydroponic growing is the rate of plant growth. Those who have tried both are routinely stunned by how quickly hydro plants are ready for harvest, not to mention their gargantuan size. However, fast growth means pruning potentially becomes more difficult. A good tactic is to remove the foliage at the bottom of your plant before it hits its flowering cycle. This process ensures that your largest buds on top of the plants receive ample energy.

Aside from the lack of soil, the main difference between hydroponically grown plants and those grown traditionally outdoors is the overall yield. In theory, outdoor farmers win this battle easily because plants can grow as high as 15 feet, with each one offering up to 10 pounds of product!

However, indoor farmers using hydroponic systems can grower thicker, more tightly packed plants that produce an impressive yield per square meter of space. As a result, you could grow hundreds of plants in a relatively enclosed space. Moreover, you have full control of irrigation, nutrients, light cycles, CO2 saturation, pests, and diseases.

If you decide to grow marijuana using a hydroponics system, be prepared for a lot of work at the beginning. You need to choose the right growing medium, nutrient solution, and equipment when starting out. Eventually,however, you will automatically know how to start the process, and from that point onwards, it gets a lot easier.

You have to monitor pH, EC, and PPM levels throughout the growth cycle, but when you have the equipment for the task, things get a whole lot easier. In the end, your hard labor will be rewarded with marijuana plants that offer a high yield and potent, flavorful weed that you can’t get enough of. Best of all, you can start growing in any room in the home.

How to Use Hydroponic Growing Systems for Marijuana
August 15, 2018
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